Hollow shaft multi-unit potentiometer



a VV/ 9 rrwl 2 Feb. 2, 1960 .1. L. JONKE HOLLOW SHAFT MULTI-UNIT POTENTIOMETER United States Patent 2,923,906 HOLLOW SHAFT MULTI-UNIT POTENTIOMETER Joseph L. Jonke, Bethpage, N.Y., assignor to Fairchild Camera and Instrument Corporation, a corporation of Delaware Application March 12, 1957, Serial No. 645,564 7 Claims. (Cl. 338-135) This invention relates generally to electrical components, and more particularly to ganged or multiple variable resistors or potentiometers having a plurality of separate resistor or potentiometer units arranged serially upon a common mounting and actuating shaft. I

In many types of electronic equipment it' is desirable, and sometimes necessary because of circuit requirements or space and weight considerations, to mount and control a plurality of potentiometers upon a single or common shaft. In some types of electronic equipment utilizing ganged or multiple otentiometers, it is necessary that each potentiometer unit wiper mounted upon the common shaft be maintained in a certain angular relationship with each of the other potentiometer wipers upon the shaft.

When the potentiometer units are first mounted upon the common shaft and each of the potentiometer units and respective wiper contact arms are set to the desired angular relationship, no diificulty ensues until it becomes necessary to repair or replace one of the potentiometer units or one of the parts thereof. In all of the prior art potentiometers of the multiple or ganged type, it has been necessary after dis-assembly and re-assembly to reset each of the potentiometer units or wiper contact arms back to the original angular relationship. The prior art devices of this general type do not provide any means for quickly dis-assembling and re-assembling ganged potentiometers or like devices without the necessity of resetting each of the potentiometers or wiper contact arms to the original desired angular relationship.

In electronic equipment utilizing ganged or multi-unit potentiometers, it is sometimes necessary or desirable to replace one or more of the potentiometer units with others having different characteristics, without disturbing the angular relationship of the potentiometer units which are not to be replaced, Known prior art devices are not capable of permitting the replacement of one or more of the potentiometer units without disturbing the settings of the remaining units.

In addition, it is sometimes desirable to change the relative angular relationship between two or more of the potentiometer wipers upon the common shaft without disturbing the angular relationship between the wipers of the remaining potentiometer units. Ordinarily such an operation would entail the removal of each of the potentiometer units from the common shaft, replacing them all upon the shaft and then resetting all of the wiper contact arms to the desired angular relationship.

- It is an object of this invention to provide a multiple potentiometer or like device having a plurality of variable units mounted serially upon a single shaft, each unit being provided with interlocking index elements so that the entire device may be dis-assembled and reassembled without the necessity of resetting the original relative positions of the individual units or their wipers.

It is another object of this invention to provide a ganged or multiple potentiometer having a plurality of Patented Feb. 2, 1960 individual potentiometer units mounted serially upon a common shaft in which the angular setting of one or more of the individual potentiometer units may be changed without dis-assembling and re-assembling the entire potentiometer and without resetting the angular positions of those potentiometer units which were not modified.

Still another object of this invention is to provide a potentiometer having a plurality of individual units serially arranged on a common shaft in which each of the individual wipers or contacts may be adjusted as to its angular position relative to the other units, and once set, the entire potentiometer may be taken apart and then reassembled without again individually adjusting the angular position of each of the wipers.

It is another object of this invention to provide a multiple potentiometer having a plurality of individual potentiometer units mounted upon a single shaft in which the wiper contact arm of each potentiometer, once set to the desired angular position relative to the other unit arms, is indexed to its proper position by an indexing or positioning element provided on the adjacent potentiometer unit on the shaft.

Still another object of the invention is to provide a potentiometer assembly having a plurality of individual potentiometer units mounted serially upon a common shaft in which each individual potentiometer unit is keyed to its desired position relative to the remaining units by means of interlocking index elements carried by each potentiometer unit.

The foregoing as well as other objects and advantages will become apparent when the following specification is read in conjunction with the appended drawings, in which:

Figure l is a vertical sectional view of a ganged or multiple potentiometer embodying this invention.

Figure 2 is an enlarged fragmentary view, partly in section, of part of the device illustrated in Figure 1, showing in more detail the leading and trailing potentiometer unit indexing and wiper arm mounting structures.

Figure 3 is a perspective view, partly in section, showing a complete end potentiometer unit as used in the ganged potentiometer of Figures 1 and 2, omitting the cylindrical cover containing the resistive strip or element.

Figure 4 is a perspective view of the hollow shaft or carrier member provided with the indexing means and upon which the wiper arm of an intermediate potentiometer unit is fitted.

Referring to the drawings and to Figure I particularly, reference numeral 10 indicates a ganged or multiple potentiometer embodying this invention and'including four separate potentiometer units mounted upon a common shaft. Although the invention is described and illustrated as comprising four separate potentiometer units, it will be apparent that more or fewer units may make up the ganged or multiple potentiometer 10. As shown in Figure 1 the potentiometer 10 comprises a lead or upper wiper unit 12, a lower end wiper unit 14, and a plurality of intermediate units 16 and 17, all of which are mounted upon a common shaft 18. Each of the wiper units 12, 14, 16 and 17 is within a cylindrical housing 20 containing a resistance element. The resistive element may be in the form of a prepared strip mounted upon the inside annular surface of each cylindrical housing, or the resistive element may be of the flat type deposited on a disc within the cylindrical housing 20. The form and type of resistive element used forms no part of this invention. Thepotentiometer unit housings 20 are held together on the shaft 18 by reason of the fact that the unit housings are connected or clamped to one another and the end plates of the end housings have bearings such as 25 for the shaft. Retaining rings and washers as at 21 and 23 locate the shaft in the axial direction.

The construction of the lead potentiometer wiper unit 12 and intermediate units 16 and -17 differs from the construction of the end 'or trailing unit 14. The construction of each of the units 12, 16 and 17 may be identical. According to the invention, the lead wiper unit 12 is indexed or keyed by means of an element affi-xed directly to the common shaft 18, while each of the following units 16, 17 and 14 is indexed to its proper position by index means cooperating with the unit preceding it upon the common shaft 18. Thus the unit 12 is indexed properly by an element carried directly upon the shaft 18, and unit 16 is indexed properly by cooperating indexing elements carried by both the units 12 and 16. In a like manner unit 17 is indexed by means of cooperating indexing means carried by both the units 16 and 17. Finally, the end potentiometer unit 14 is indexed properly by means of coopcrating indexing elements carried by both units '17 and 14.

In the lead potentiometer unit 12 there is provided a metal wiper contact arm 22 for sliding or wiping contact with the resistive element contained in the cylindrical housing 20. The wiper contact arm 22 is integral with and extends outward from a metal ring 24 encircling an insulating sleeve 28. The ring 24 is secured to the lower portion of the insulating sleeve 28 as by friction, cementing or by means of rivets 26 or the like. The insulating sleeve 28 is securely bonded by any suitable means upon a cylindrical metal reinforcing bushing 30. The metal reinforcing bushing 30 iszpreferably the same length as the insulating sleeve which is mounted thereon, and the two are bonded or fitted together in such manner as to prevent any relative rotation or movement between these two parts so that in effect they form an integral unit. This unit is mounted upon a hollow shaft or carrier member 32 so that it may slide or rotate thereon for adjustment purposes, but may be securely affixed thereto to prevent'such motion after adjustment is made. The carrier member 32 is considerably longer than the bushing 30 and its insulating sleeve 28, and may be provided at its upper end with a locating shoulder 34 above which extends an indexing or keying semi-circular portion 36. The vertical edge (such as 38) of the indexing portion 36 abuts against an indexing pin or lug 40 extending through the shaft 18. The lower end of the carrier member 32 is provided with an extending semi-circular indexing portion 42 for cooperation with the next wiper unit on the shaft 18 in a manner to be described below.

The carrier member -32 is of such internal diameter that it may slide upon or rotate upon the shaft 18 and be indexed or keyed to its proper position by means of the indexing pin 40 and the cooperating edges 38 of the semi-circular indexing portion 36 on the carrier member itself. It is secured from any axial movement relative to the shaft 18 and locked thereto in a manner to be described below. The wiper 'arm 22 together with its sleeve 28 and bushing 30 may be :rotated to the desired :"angular position and then secured against "any movement relative to the carrier member 32 by means of a setscrew 48 in a radial threaded opening in the upper portion of the sleeve 28 and the bushing 30. When the desired initial angular position of the wiper arm 22 is obtained, it is then secured from any motion relative to the carrier member 32 by tightening the setscrew 48 down until it bears strongly against the carrier member 32.

The end potentiometer unit 14 is similar in some respects to the lead potentiometer unit 12 in that it too is, provided with a wiper contact arm 52 extending from :a ring element -54 encircling an insulating sleeve 58 and atfixed thereto as by friction, cements or by rivets 56. As in the lead unit 12, the insulating sleeve 58 is securely bonded by any suitable means upon a cylindrical metal bushing 60 to form an integral unit. The ring element 54 is shown as secured to the top portion of the sleeve 58. The hollow shaft or carrier member 62 is similar in many respects to the carrier member 32 utilized in the lead unit 12, having a location shoulder 64 at the upper end thereof and a projecting semi-circular indexing portion 66. The leading edge of the semi-circular indexing portion 66, designateda's' 68, is rounded for ease in engagement with the vertical edge at 42 of the preceding carrier element. The upper portion of the carrier member 62 is preferably provided with vertical slots 70 to insure a certain amount of spring action when the rounded edge 68 is brought into contact with the vertical edge of the preceding carrier member as the end potentiometer unit 14 is slid along the shaft 18 to abut the unit ahead of it. The carrier member 62 is provided near its lower extremity with a horizontal arcuate slot 72 extending approximately 180" around the circumference thereof. The wiper arm 52 carried by the insulating sleeve 58, and its integral metal bushing 60, once adjusted to its desired position relative to the carrier member 62, may be secured against any motion relative thereto by means of a setscrew 74 inserted into a threaded opening through the sleeve 58 and the metal bushing 60. By tightening the setscrew 74 against the carrier member, the wiper arm 52 is prevented from any motion relative thereto. After the carrier member 62'has been indexed and positioned properly it may then be secured against any motion relative to the shaft 18 by means of a setscrew inserted into a threaded opening extending through the sleeve 58 and the metal bushing 60 to coincide with the arcuate slot 72. By tightening the setscrew 80, the carrier member 62 and all that is mounted thereon is secured against any movement relative to the shaft 18. To enable such locking action for any desired setting of the wiper contact arm, a plurality (for example, three) of such setscrew holes are located around the peripheryof the carrier member 62 so that at least one set screw hole always will coincide with the arcuate slot 72. The careach of thesethree carrier members is provided with a, semi-circular indexing portion at its lower end identical with the indexing portion 42 extending from the lower end of the carrierm'ember '32 of the lead unit 12, but" differ from unit 14 in the omission of the arcuate slot 72 at the lower portion thereof. Figure 4 illustrates a carrier member '32 such as is used in each of the units 12, 16 and 17. The carrier member 32 is provided at its upper end with a shoulder 34 and the semi-circular indexing portion '36 having rounded edge 82 and vertical slots84 cut through the upper half of the carrier member 32 to provide the desired spring action 'to the indexing;

portion 36. The lower end of the carrier member 32 is provided with the extending semi-circular indexing por-' tion 42 which is to be contacted by the semi-circular portion on the upper end of the following carrier member such as that of unit 17 From this description it is clear that the construction of the hollow shaft or carrier member 32 used in each of the units 12, 16 and '17 is identical to the carrier member 62 used in'the end unit with the exception that the carrier member 32 isprovided with-an indexing portion32 at its lower end, and that the arcuate slot 72 may be omitted.

Each of the intermediate units 16 and 17 is provide'cle with a wiper contact arm mounted upon an insulating sleeve which is reinforced by a metal bushing identical in structure to that already described in connection with the lead unit 12 and the end unit 14. The wiper contact arm assembly may be adjusted as to its desired initial angular position and then secured to its hollow shaft or carrier member in a manner already'described in connection with the other wiper units.

In assembling the potentiometer, the lead unit 12- is pushed upon the shaft 18 until the upper portion of the carrier member 32 engages the index pin 40. The carrier member is then rotated until the vertical edges such as 38 abut against the index pin 40 as shown in Figure 1. The contact wiper arm 22 is then rotated to the desired initial angular position and the setscrew 48 is tightened, thus 'locking the wiper arm 22, the insulating sleeve 28 and its metal bushing 30 against any movement relative to the carrier member 32.

An intermediate unit is then pushed upon the shaft 18 until the rounded edge 82 of the indexing portion 36 of the carrier member 32 contacts and abuts the indexing section 42 of the lead unit carrier member 32. The rounded edge 82 and the slots 84 case the proper interfitting of the unit. The wiper contact arm is set to the desired initial angular position, and the setscrew holding the Wiper arm, its insulating sleeve and metal bushing against movement relative to the carrier member 32 is tightened.

The next intermediate unit such as 17 is pushed upon the shaft 18 and is indexed to its proper position by means of the cooperating index elements as described in connection with the intermediate unit 16. After the two intermediate units 16 and 17 are pushed upon the shaft 18 as far as they will go and are indexed properly, the end unit 14 is pushed on the shaft 18 to abut the unit 17 and be indexed thereby. The wiper contact arm 52 of the end unit 14 is then set to the desired initial angular setting and the wiper arm setscrew 74 is tightened to lock the arm in its desired setting. The setscrew 80 positioned to pass through slot 72 is tightened against the shaft 18. This locks the end unit 14 against any axial or rotary movement relative to the shaft, because all of the units are interlocked by their respective indexing elements.

It is obvious that by loosening only the setscrew 80 holding the hollow shaft or carrier member 62 of the end unit 14 to the mounting shaft 18, all of the potentiometer units may be removed and thereafter re-assembled upon the shaft 18 without the necessity of again setting the wiper contact arms to the desired initial angular relationship, because each of the units is indexed to its preset original angular position by means of the indexing elements on each of the potentiometer units. By means of the construction just described it is also possible to adjust the relative angular position of one or more of the wiper arms without disturbing the setting of the remaining units, all While the units, remain assembled upon the common shaft.

It is important in removing the end potentiometer unit 14 from the shaft 18 that only the setscrew 80 holding the hollow shaft or carrier member 62 be loosened. If the setscrew holding the wiper arm is loosened, the original or initial arm setting will be lost. For this reason the setscrew 74 holding the wiper arm against motion relative to the end unit carrier member 62 may be marked in a special way as a warning that such setscrew should not be loosened except to change the wiper arm setting; or a setscrew 80 requiring a different wrench size may be provided.

For economy in manufacture, the hollow shaft or carrier members for each of the intermediate units as well as the end units may be made identical, even though there is no need for a dcnending indexing portion 42 on the end carrier member 62, or for a slot 72 in the upper carrier members 32. By making all of these carrier members alike, only one type of carrier member need be made and stocked. In addition, all of the wiper arm assemblies may be made alike in that the same number of setscrew openings may be drilled and tapped in each one regardless of whether or not all of the openings will be used. In this manner all of the wiper arm assemblies maybe turned out with a minimum of tooling, and the stock problem is simplified.

Although the invention has been described and illustrated in connection with multiple potentiometers, the invention may be used equally as well for other types of multiple electrical components such as variable resistors, variable condensers, and for ganged rotary switches of the multiple contact type. In these types of components this invention is of great value since a series of ganged rotary switches may be dis-assembled from the common shaft and re-assembled again on the shaft without the necessity of resetting the relative angular positions of each wiper contact arm, a considerable saving of time and effort.

The carrier members on which the wiper arm assem-' blies are mounted need not necessarily be in an elongated form, as illustrated in the preferred embodiment, but may be much shorter and still accomplish the desired result. That is, the sub-assemblies may be made in proportions more nearly disc-like than cylindrical.

While there has been described and illustrated a prcferred embodiment of the invention and its mode of operation and assembly, it is obvious that various changes may be made in the illustrated embodiment without departing from the scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a multiple unit electrical component having a plurality of individual adjustable contact units serially and loosely mounted upon a common shaft, interlocking indexing means carried by each of said individual units whereby the relative angular position of each of said units is determined by the preceding unit upon the common shaft, and means extending through one of said units for releasably securing all of the interlocked units to said common shaft.

2. A multiple unit electrical component comprising a plurality of units each including a member carrying a wiper contact rotatable to select values of an electrical parameter, said units being assembled in end to end relation with their members rotatable on a common shaft, each wiper contact being mounted on a member for independent adjustment of said wiper contact on said member, means for releasably locking all of said members to one another in predetermined positional arrangement, and means carried by and extending through one end member for securing the interlocked members as a unit to said shaft.

3. A multiple unit electrical component comprising a plurality of individual units each including a member carrying a wiper contact rotatable to select values of an electrical parameter, said individual units including a lead unit, at least one intermediate unit, and an end unit, said units being serially and loosely mounted upon a common shaft, index means for said lead unit mounted upon said shaft, cooperating index elements on each of said units whereby each unit is properly positioned on said common shaft by the unit preceding it upon the common shaft, and means carried by and extending through said end unit for releasably securing all of said units as a whole to said shaft.

4. A multiple potentiometer having a plurality of individual potentiometer units serially mounted upon a common shaft, each of said units including a carrier member capable of sliding and rotary movement upon said shaft, means for releasably securing all of said carrier members to one another upon said shaft in predetermined positional arrangement, a wiper arm assembly adjustably mounted on each of said carrier members, and means for releasably securing said carrier members as a group to said shaft, .said last mentioned means extending through the \last of said carriermembers to grip the common shaft. I

-5. A multiple potentiometer having a plurality of individual potentiometer units serially mounted along a common shaft, each of said units including a carrier member capable of sliding and rotary movement upon said shaft, a wiper arm assembly so mounted to its carrier member as to prevent relative motion therebetween, an indexing element on each carrier member for cooperation with the succeeding carrier member on said shaft for releasably securing all said carrier members to one another in a predetermined positional arrangement upon said shaft, and means extending through an end carrier member for releasably locking said carrier members as a unit to said shaft.

6, A multiple potentiometer having a plurality of individual potentiometer units serially mounted upon a common shaft, each of said units including a carrier member capable of sliding and rotary movement upon said shaft, means for releasably securing all of said carrier members to one another upon said shaft in predetermined positionallarrangement, a wiper arm assembly adjustably mounted on each of said carrier members, means mounted upon and extending through each said wiper arm assembly forlocking the wiper arm assembly in the desired 8. position on its carrier member, and means for releasably securing said carrier members as a group to said shaft, said last mentioned means extending through an end one of said carrier members to .grip the common shaft.

7. A multiple unit electrical component comprising a plurality of units each including an angularly adjustable wiper contact element rotatable to select values of an electrical parameter, a member carrying each wiper contact element, means mounted upon and extending through each said wiper contact element to its member for locking said element in a desired angular position, said .units being assembled in end to end relation with their members rotatable on a common shaft, means for releasably looking all said members to one another in predetermined positional anrangernent, and means carried by and extending through an end one of said members for securing the interlocked members as a unit to said shaft.

References Cited in the file of this patent Burgess May 29, 1956 

